Threadless type well tubing safety joint



22, 196 3. I J. ETAL 3,10%930 mmbmss TYPE WELL TUBING SAFETY JOINT FiledSept. 25, 1959 M r am a/ m m M L5 J i Z a (/06 14/. G/bbs I'll lrllllI'll ATTORNEY United States Patent Oftice 3 1 7,9 Patented Get. 22, 19633,197,930 THREADLESS TYPE WELL TUBING SAFETY JUBNT .ioe W. Gibbs, 3834Merrick, Houston, Tex.; Charles I. McKiearnan, 4239 Wayside, Odessa,Tex.; and Philip E.

Davis, in, M202 Kittreil, Houston, Tex.

Filed Sept. 25, 1959, Ser. No. 842,500

4 Claims. (Cl. 285-45) This invention relates to so-called safety jointsfor well tubing or casing strings, which facilitate intermediatelysevering the string to permit removal from the well of the upper partonly thereof.

Previous safety joints have involved either threaded couplings whichrequire rotation of the part of the tubing string which is to beremoved, or weakened elements which may be torn apart by longitudinaljarring action. The first type is not always practical, particularlywhere projections on the tubing, such as gas lift valves, preventrotation thereof. The second type have the disadvantage of constitutinga permanent weakness in the tubing string which may not carry forcesincident to normal running and supporting of the string. Furthermore,there has been no practical way to reassemble the unthreaded or severedtubing strings, except with the use of an overshot coupling which mayrequire more well space than is available.

Accordingly, the main object of the present invention is to provide atubing or casing safety joint device which avoids the above stateddisadvantages.

A more detailed object is to provide a safety joint which may be severedby the use of a commercial tubing or casing cutter, either of themechanical or chemical type, without damaging the juxtaposed portion ofthe joint which remains with the set tubing or casing.

Another object is to provide a safety joint which may be reassembledafter the severing operation, yet which is full opening internally andof substantially the same external diamension as a tool joint orcoupling.

Stfll another object is to provide a safety joint which does not involvea portion which is so structurally weakened as not to resist normalrunning and supporting forces applied to the tubing or casing string.

These objects and others are accomplished inmy novel safety joint whichconsists, essentiflly, of end portions for connection in the tubing orcasing string and one or more tubular, telescoped, intermediate memberswhich ar structurally secured to the end portions of the joint. Theintermediate member, or one of them, has a restricted, relieved portionpermitting cutting thereof by a commercial tubing or casing cutting toolwithout damaging the juxtaposed joint structure. After severing, theupper portion of the joint and attached tubing or casing string may bewithdrawn. Sealing means are provided between the separable portions ofthe joint so that these portions may be sealingly re-engaged. In thepreferred form, a pair of intermediate members are provided which mounta one-way latch structure which prevents longitudinal separation of thecoupled pipe strings, yet permits the severed remnant of the cut memberof the joint to be displaced longitudinally to permit substitutiontherefor of a replacement member with coupled upper string portion.

In the accompanying drawings which illustrate the invention:

FIG. 1 is an elevation partly cut away and sectioned, illustrating thenovel safety joint inserted in a tubing string;

FIG. 2 shows the joint in severed condition and with the upper portionlongitudinally separated therefrom; and

FIG. 3 is a view, substantially enlarged, showing the couplingreassembled with a replacement for the severed member thereof.

The novel coupling device or safety joint consists of upper and lowerend portions or subs 5 and 6, the former being internally threaded forattachment to the threaded lower end of tubing 7. The lower portion 6 isexternally threaded for attachment by means of a coupling 8 t tubing 9.The device also includes a first, tubular, intermediate member orrelease nipple 10 which is threadedly secured at its upper extremity tothe lower end of joint end portion upper sub so that, in elfect, parts 5and lil form a rigidly connected, continuous inner tubular member.Telescopingly received about first intermediate member is a second,tubular, intermediate member or landing bushing 1'1 which is threadedlysecured at its lower or telescoped extremity 12 to the upper end ofjoint lower end portion 6. Parts 11 and 6, thus form a continuous,tubular outer member having a smooth faced inner Wall normally slidablyfitting the similar outer wall of inner tubular member 5, 10. Annularshoulders Nd and 11a, respectively, on members 10 and 11, limit relativemovement of these members in one direction, that is, together. O-ringseals 13 and 14 are provided between the intermediate members and thejoint end subs 5 and 6 secured thereto. The upper or telescopedextremi-ty 15 of landing bushing 11 slidably receives by stab type fitthe adjacent portions of release nipple 1i and joint upper sub 5 and asealing packing '16 is provided therebetween. The inner face of portion'12 of bushing 11, between its extremities, is provided with arestricted, radially relieved portion 17 which permits severing of therelatively thin adjacent part 1042: of the release nipple, as by meansof a chemical cutter represented at '18, without substantially damagingthe juxtaposed part of outer member 11. The cutter is provided withpositioning fingers 19 which cooperate with coupling clearance space 20.Cutter 18 has an annular series of holes 22 through which chemicalcutting material is forcefully ejected for ture consists of a split ringor nut, generally indicated at 24, having a downwardly and outwardlytapered outer surface 25 (FIG. 3) which snugly seats in a complementarysimilarly inclined cam element 12a provided at the lower end of outermember 11, 12. The inner surface of the split ring is provided with abuttress thread or ridging 26 with axial force-transmitting lower faces27 at an angle of substantially more than 45 to the axis of the joint,preferably normal or nearly normal thereto. The intermediate faces .28of the thread are at angles of substantially less than 45 'with thejoint axis. The threads 26 on the latching ring couples With thesimilarly shaped threads 10b on the lower portion 10a of inner orrelease nipple member 10. Split ring or nut 24- extends substantiallybelow the lower end of outer member 11 into a clearance 29 providedtherefor in the inner Wall of joint lower end portion 6. The lower wallof recess 29 is defined by a radial shoulder 31, while the inclined camsurface 12a bounds the top of the recess. This clearance permitssufficient circumferential expansion'of split ring or nut structure 24to permit the lower extremity of inner or release nipple member 10 to bestabbed thereinto and to be displaced longitudinally therethrough aswill be explained hereafter. A circular spring 32 received snugly aboutsplit ring 24 resiliently resists expana sion thereof. It iscontemplated that the nut structure will be threaded upon thelower endof member 10, but the mating faces of the nut structure and part 10acould readily be provided with ugh-spiral ridging and/ or groovingshaped in section-like the buttress threads. In this case, the initialassembly would be made by driving the split ring structure endwise uponthe reduced lower end 100 of member 10.

Upon severing of release nipple member 10 by means of a suitable cutter,the upper portion of the nipple and the coupled upper portion of thetubing string may be Withdrawn upwardly, as shown in FIG. 2. The remnant169a or the severed release nipple member is maintained in position bylatching nut structure 24. In order to reassemble the safety joint, theupper severed portion of the release nipple member is unscrewed fromjoint upper end portion 5, after (this portion of the string is removedfrom the well, and a replacement release nipple member We substitutedtherefor with renewed packings 16a and 13a. 'l hereupon, tubing string 7is reintroduced into the well and the reduced lower extremity ofsubstitute nipple member 100 guided or stabbed into the open, upper endof landing bushing member 1 1. The serated or buttress threaded lowerextremity of substitute nipple 100 is forced through split latch nutstructure 24 until the upper end of landing bushing 11 seats againstshoulder 30 provided therefor in joint upper end portion 5. At suchtime, renewed sealing packing 16a will prevent leakage between thelanding bushing and the received portions of joint end portion andsubstitute member 1G0. Clearance 29 will permit sufficient radialexpansion of the nut structure to permit interlatching with substitutemember 100; The shape of the serations or teeth pro vided on nutstructure 24 will, of course, ltensionally secure together, that is,prevent longitudinal separation of joint end portions 5 and 6 and thecoupled tubing or casting strings. FIG. 3 also more clearly shows theradially relieved restricted annular zones 17a in the inner wall of thethreaded intermediate part 12 whereby member 16c may be severed, asbefore, if necessary. Nut structure 24 may consist of annularlyarranged, separate segments, in the manner of. wedging slips. The noveljoint, may be inserted in a casing string instead of the tubing stringas shown. The invention may be modified in this and other respects aswill occur to those skilled in the art and the exclusive use of allmodifications as come within the scope of the appended claims iscontemplated.

What is claimed is:

l. A safety joint for pipe strings comprising outer and inner tubularmembers having smooth faced adjacent wall surfaces adapted to receive bya stab type fit the inner tubular member within the outer tubular memberwith the tubular members being in telescoping relationship relative toeach other,

means for limiting relative travel or the tubular members in a givendirection,

said inner tubular member having a series of connected surfaces eachinclined toward the axis of the inner tubular member and definingannular latching elements,

a substantially radial shoulder on the inner wall of the outer tubularmember for defining one wall of an annular recess therein,

an upwardly and inwardly inclined wall axially spaced from said shoulderfor defining another wall of said annular recess,

said annular recess in the outer tubular member being disposed adjacentthe annular latching elements of the inner tubular member when saidtubular members are disposed in the telescoping relationship by the stabtype fit,

resilient annular latching structure expandably an .4 contractablydisposed within the confines of the annular recess,

said latching structure having a series of connected surfaces fordefining ;complcrnentary latching elements disposed in cooperatingrelationship with the latching elements of the inner tubular member,

cam means defined by the outer peripheral portion of the annularlatching structure for engagement with the inclined wall of the recessin the outer tubular member,

said cam means being etfective to urge the latching elements of theannular latching structure into interlocking engagement rwith thelatching elements of the inner tubular member on relative movement ofthe tubular members in the given direction while restraining relativemovement of the tubular members in another direction that is opposed tothe given direction,

a device establishing a locale for enabling an end portion of the innertubular member to be severed therefrom without substantial damage to theouter tubular member,

said locale being at a location which is a given distance from the endportion of the inner tubular member when said tubular members aredisposed at the limit of telescopic travel, and

an arrangement for receiving an end portion of the inner tubular memberafter such end portion there- 7 of has been severed therefrom, saidarrangement extending from the end portion of the inner tubular memberwhich is to be severed and terminating a distance therefrom which is atleast equal in extent to the given distance that the locale of thedevice is located from the end portion of the inner tubular member withthe arrangement being of sufiicient size to accommodate the end portionof the inner tubular member after the end portion has been severedtherefrom, said tubular member and the latching structure disposed inthe recess defined by the shoulder and the inclined wall of the outertubular member together with the latching elements, the cam means, thedevice and the arrangement being constructed and arranged to enable theend portion of the inner tubular members to be severed adjacent thedevice and then urged by a replacement inner tubular member past thelatching structure into the said arrangement. 2. A safety joint asdescribed in claim 1 in which said latching structures is in the form ofa discontinuous ring and further includes spring means resisting radialexpansion of said structure. 7

3. A safety joint as described in claim 1 in which said complementarybuttress elements are formed as buttress threads constructed to resistrelative movement of said tubular members in said opposite directionwhile enabling relative motion in said first direction between said endportion of said inner member, when severed, and said latching structure.

4. A safety joint as described in claim '1 in which said inner tubularmember is formed of two separable parts,

a first for attachment to the pipe string and asecond at-v tached tosaid first part and including said severable end portion.

Sweetrnan Dec. 22,

1. A SAFETY JOINT FOR PIPE STRINGS COMPRISING OUTER AND INNER TUBULARMEMBERS HAVING SMOOTH FACED ADJACENT WALL SURFACES ADAPTED TO RECEIVE BYA STAB TYPE FIT THE INNER TUBULAR MEMBER WITHIN THE OUTER TUBULAR MEMBERWITH THE TUBULAR MEMBERS BEING IN TELESCOPING RELATIONSHIP RELATIVE TOEACH OTHER, MEANS FOR LIMITING RELATIVE TRAVEL OF THE TUBULAR MEMBERS INA GIVEN DIRECTION, SAID INNER TUBULAR MEMBER HAVING A SERIES OFCONNECTED SURFACES EACH INCLINED TOWARD THE AXIS OF THE INNER TUBULARMEMBER AND DEFINING ANNULAR LATCHING ELEMENTS, A SUBSTANTIALLY RADIALSHOULDER ON THE INNER WALL OF THE OUTER TUBULAR MEMBER FOR DEFINING ONEWALL OF AN ANNULAR RECESS THEREIN, AN UPWARDLY AND INWARDLY INCLINEDWALL AXIALLY SPACED FROM SAID SHOULDER FOR DEFINING ANOTHER WALL OF SAIDANNULAR RECESS, SAID ANNULAR RECESS IN THE OUTER TUBULAR MEMBER BEINGDISPOSED ADJACENT THE ANNULAR LATCHING ELEMENTS OF THE INNER TUBULARMEMBER WHEN SAID TUBULAR MEMBERS ARE DISPOSED IN THE TELESCOPINGRELATIONSHIP BY THE STAB TYPE FIT, RESILIENT ANNULAR LATCHING STRUCTUREEXPANDABLY AND CONTRACTABLY DISPOSED WITHIN THE CONFINES OF THE ANNULARRECESS, SAID LATCHING STRUCTURE HAVING A SERIES OF CONNECTED SURFACESFOR DEFINING COMPLEMENTARY LATCHING ELEMENTS DISPOSED IN COOPERATINGRELATIONSHIP WITH THE LATCHING ELEMENTS OF THE INNER TUBULAR MEMBER, CAMMEANS DEFINED BY THE OUTER PERIPHERAL PORTION OF THE ANNULAR LATCHINGSTRUCTURE FOR ENGAGEMENT WITH THE INCLINED WALL OF THE RECESS IN THEOUTER TUBULAR MEMBER, SAID CAM MEANS BEING EFFECTIVE TO URGE THELATCHING ELEMENTS OF THE ANNULAR LATCHING STRUCTURE INTO INTERLOCKINGENGAGEMENT WITH THE LATCHING ELEMENTS OF THE INNER TUBULAR MEMBER ONRELATIVE MOVEMENT OF THE TUBULAR MEMBERS IN THE GIVEN DIRECTION WHILERESTRAINING RELATIVE MOVEMENT OF THE TUBULAR MEMBERS IN ANOTHERDIRECTION THAT IS OPPOSED TO THE GIVEN DIRECTION, A DEVICE ESTABLISHINGA LOCALE FOR ENABLING AN END POR-